Brushless motors have become ubiquitous in the consumer market. Due to their inherent efficiency, low-maintenance, and power-to-weight ratio, brushless motors are the de facto standard for many electric propulsion systems. However, virtually all brushless control systems on the market today use an inefficient speed control method called scalar control (also known as trapezoidal control). Scalar control, while inexpensive and easy to implement, is plagued by a number of issues, including low torque production, high torque ripple, vibration and noise, low energy efficiency and decreased motor life. It would be desirable to resolve one or more of these issues by using a sensorless field-oriented control (FOC) algorithm. Field-oriented control of brushless electric motors has not been successfully implemented in a miniaturized, battery-powered system designed for use with personal electric vehicles.
An electronic speed controller is disclosed to control a motor that powers a motor load. The electronic speed controller includes a motor port, a throttle port, a power port, a processor and a memory. The motor port is configured to send motor commands to the motor and receive motor inputs from the motor. The throttle port is configured to receive user commands. The power port is configured to receive power to power the speed controller. The processor is configured to receive the user commands and the motor inputs, and to generate the motor commands based on the user commands and the motor inputs. The memory is configured to store data for use by the processor.
The electronic speed controller can also include an external accessories port configured to send accessory commands to an external accessory, and to receive accessory inputs from the external accessory. The electronic speed controller can also include a data communications port configured to communicate with external applications. One of the external applications can be a motor identification system with a plurality of sets of motor parameters, where each set of motor parameters characterizes a particular motor type.
The motor port can include a motor analog-to-digital converter (ADC), wherein the motor ADC is configured to receive the motor signals in digital form from the processor and transform those motor signals to analog form to send to the motor, and the motor ADC is configured to receive the motor inputs in analog form from the motor and transform those motor inputs to digital form to send to the processor. The throttle port can include an analog-to-digital converter (ADC) throttle input port and a pulse-width modulation (PWM) throttle input port configured to receive the user commands from a throttle unit.
A field oriented control method for a motor is disclosed where the motor is a three-phase permanent-magnet synchronous motor (PMSM). The field oriented control method includes continuously monitoring stator voltages and currents from each of the three motor phases; accessing motor parameters for the motor; using a mathematical model of the motor to calculate rotor flux, rotor angle and rotor speed based on the stator voltages and currents from each of the three motor phases and the motor parameters; receiving user commands for the motor; and generating motor commands for controlling the motor based on the user commands and the calculated rotor flux, rotor angle and rotor speed.
Additional inventions are also described in the detailed description that follows and the figures.
Corresponding reference numerals are used to indicate corresponding parts throughout the several views.